IIRC, this Jackass holster fits any Glock EXCEPT for the slim-line pistols (e.g. Glock 42, 43, 43X, etc). My Glock 17, Glock 19, and Glock 26 each carry very nicely with this rig.
NOTE: I just checked the Galco site for which Glocks fit this rig:
JR224B also fits the following guns:
GLOCK 17 Gen 1-5, 19 Gen 1-5, 19X, 22 Gen 2-5, 23 Gen 2-5, 26 Gen 3-5, 27 Gen 3-5, 31, 32, 33, 34 Gen 3-5, 35, 45
The magazine pouch holds a pair of any Glock full size double-stack standard-capacity mags (a 33-round 9mm mag is far too long). The mag retention-straps have a spare snap to accommodate the shorter Glock 26 mags; that's a very nice design feature. The pouch's main-retention of the mags is via the straps; the native-retention of the mags is adjustable; properly set, the native-retention keeps gravity from sucking the mags out of the pouch while still allowing the shooter easy mag withdrawal.
I have the black leather tie-downs for both the gun-side and the magazine-side of this rig (a separate purchase) but I rarely choose to use them. If I'm performing tasks that might require me to be flat on the ground I wear the tie-downs.
The Jackass style holster rides at more of an angle than do the other Galco horizontal holsters. For those folks having thin torsos (front to back) the butt-down / muzzle-up angle of the dangle helps conceal the longer Glock 17 and 19 size pistols. Some pistoleros feel that the butt-down angle provides for a more natural draw stroke.
The main retention of the pistol is provided by the holster's very substantial retention strap. The holster's native-retention of the pistol is adjustable via a screw below the trigger guard. If it is too tight you can tug like hell and that pistol isn't going anywhere; if it is set too loose the pistol can fall out if the thumb release on the retention-strap is accidentally tripped. The adjustable native-retention is a very nice feature to have. Today I was having a rather animated battle with the snow (I was wrestling a monster size blower along with intermittent sessions with snow-shovels). At some time or another I did something that tripped the holster's retention-strap thumb-release; the pistol stayed secure; I didn't notice that the strap was undone until I went back in the house. Good holster design and quality build does make a difference.
(Yeah, we got another 5'' of snow last night)
I'm old and overweight but my torso still has enough of a taper to provide hollow areas for the holster and the mag pouch to reside. I prefer both to be at the inside of the elbow or just barely up a bit from there. Some folks prefer them high-and-tight in (or just below) the armpit; I find that area to be very uncomfortable for concealed carry.
I've periodically carried my G17, G19, and G26 while wearing this rig during spring, summer, fall, and winter while performing heavy physical tasks normally associated with each of those seasons. For me, this rig is a big-time winner; your mileage may vary. I will admit that I much prefer to carry and dress as light as possible during the dog days of summer; that is the most difficult time of year for me to be sporting this rig but it is tolerable.
Keep a cool head.
Please practice safe gun handling and storage.
Peace be with you.